February fireballs really shake things up

Security video captured the Canadian fireball over Saskatchewan, Alberta, Canada

Meteorites seem to be dropping everywhere. First China and now today comes word of fresh cosmic booty on the ground north of the town of Rockhaven (a wonderfully appropriate name) left in the wake of a brilliant fireball that appeared over Alberta, Canada this past Tuesday evening.

The meteor was described as blue-white and as bright as the moon. Some went even further and compared it to the sun. Observers reported hearing low rumbling noises for several minutes after it broke up and disappeared. These are all good signs that material survived the fiery, high pressure flight through Earth’s atmosphere. The first specimens of what appears to be a very fresh meteorite were picked up not long after the fall on a road north of Rockhaven and can be viewed HERE. Yes, one of them is already up for sale!

Another fireball, this time recorded by NASA’s All-Sky Camera in Georgia on Feb. 13

The Rockhaven fall is just one of about a half dozen bright fireball sightings in North America this month. While that number isn’t unusual, their very slow speed and deep penetration into the atmosphere is. Their incoming speed has been around 32,000 mph followed by a rapid deceleration and burnout at some 31 miles high.

A fireball streaks through the sky. Fireballs are defined as meteors brighter than the planet Venus. Credit: John Chumack

“This month, some big space rocks have been hitting Earth’s atmosphere,” says Bill Cooke of NASA’s Meteoroid Environment Office. “There have been five or six notable fireballs that might have dropped meteorites around the United States.” The first one briefly lit up the sky over Dallas-Ft.Worth, Texas on February 1, wowing thousand with a sputtering light as bright as a full moon.

The incoming meteoroids – as they’re known before breaking up and potentially landing as meteorites on the ground – range in size from “basketballs to buses”. When astronomers analyzed their orbits based on photos and eyewitness observations, they all trace back to various locales in the asteroid belt between Mars and Jupiter. Most meteorites are thought to originate from collisions between asteroids that ultimately send fragments toward the Earth and other planets.

Because of this year’s numerous sightings as well as those made by both amateurs and professionals in Februaries past, some astronomers suspect that a stream of meteors they’ve nicknamed the “February Fireballs” intersect Earth’s orbit this time every year. Some studies show a correlation, some don’t. We may soon get a more definitive answer thanks to a network of night eyes.

One of NASA's all-sky cameras keeps watch on the night sky. Credit: NASA

There are currently six all-sky cameras operated by NASA’s All-Sky Fireball Network in north Alabama, northwest Georgia, southern Tennessee and southern New Mexico with many more in the planning stages. Like the ever-watching eye of Sauron in the Lord of the Rings story (sorry for the dark analogy), the cameras photograph the sky with fisheye lenses all night long. When a fireball is seen by more than one camera, astronomers can triangulate its height, speed and even determine an orbit. And once you know an orbit, you can trace the cosmic rock back to its ancestral home.

Scientists estimate that 37,000 to 78,000 tons of meteorite material falls to Earth each year. That number sounds huge, but remember that most meteoroids are broken up into dust from the profound heating and pressure experienced during atmospheric entry and never make it to the ground.

According to NASA astronomer Dr. Steve Odenwald, the Earth intercepts 19,000 meteoroids weighing over 3.5 ounces every day. Of these, only about 10 are recovered by human hunters each year. Our planet is big, very big, and much of what falls does so in the oceans unseen by nearly everyone. That’s what makes finding a meteorite – especially one from a fresh fall – so rare.